Malformed Frogs

The Collapse of Aquatic Ecosystems

Michael Lannoo

Publication Year: 2008

The widespread appearance of frogs with deformed bodies has generated much press coverage over the past decade. Frogs with extra limbs or digits, missing limbs or digits, or misaligned appendages raise an alarming question: "Are deformed humans next?" Taking a fresh look at this disturbing environmental problem, this reference provides a balanced overview of the science behind the malformed frog phenomenon. Bringing together data from ecology, parasitology, and other disciplines, Michael Lannoo considers the possible causes of these deformities, tells which frogs have been affected, and addresses questions about what these malformations might mean to human populations. Featuring high-quality radiographic images, Malformed Frogs suggests that our focus should be on finding practical solutions, a key component of which will be controlling chemical, nutrient, and pesticide runoff into wetlands.

Cover

Title Page, Copyright, Dedication, Quotes

Contents

Preface

Attending scientific meetings may be the least professional thing that scientists
do. Meetings are a lot about personal interactions, and the outcomes
of personal interactions are dependent on attributes such as gender (males
tend to have an advantage), size (increased height is more influential than
increased weight), ...

Acknowledgment

This book wrote itself in a matter of a few months. Given the often
demonstrated inverse relationship between time spent and errors generated,
and the opposite, direct relationship between eyes observing and
perspective achieved (faculty meetings excepted), ...

Introduction

As a cultural phenomenon it began in the summer of 1995 in south-central
Minnesota, with school kids on a field trip.2 While exploring a rural wetland,
Cindy Reinitz and her junior high school students discovered a large
number of northern leopard frogs (Rana pipiens) that were having trouble
jumping. ...

1. What is an Amphibian Malformation?

The word “malformation” literally means “bad form.” Bad form in most
animals means an unintended lack of symmetry, or an imbalance in structure,
color, or other quality. A lack of symmetry can arise through one
of three mechanisms:2 ...

2. Malformed Frog Types

In an attempt to organize, and to correlate effect with cause, malformations,
whether human, frog, or otherwise, have tended to be divided into
types. Malformation types are almost always based on: (1) structures absent
or reduced, (2) structures duplicated (or multiplied), and (3) structures
present but otherwise abnormal ...

3. Hotspots

In amphibian conservation biology, the term “hotspot” is used in two
contrasting ways. One way, with a good implication, is to denote a site
or a region with high amphibian richness. These places are usually located
in tropical or subtropical ecosystems and are often the focus of intense
conservation efforts. ...

4. Causes

The year 2006 marked the 300th anniversary of known published observations
of malformed frogs. The recognition that malformed frogs preceded
the beginning of the Industrial Revolution by about 150 years and
preceded modern agricultural techniques (including the application of
pesticides) ...

5. Resolutions

There has been nothing tidy about the malformed frog investigation. Examining
the field, some workers have chosen terms like the “complexity
of deformed amphibians”2 or an “eco-devo riddle”3 as descriptors. At face
value this is true, but I gently disagree that we need more data. ...

6. Human Malformations and Causes

The fear that what was happening to frogs could happen to humans is the
major reason why the malformed frog problem tipped in 1996. As with
many ways of thinking about malformed frogs, the logic behind this concern
is sound. Something in the water is causing frog malformations; ...

7. Solutions

Why is it that when human congenital malformations are addressed, the
full suite of abnormalities and the full range of causes are considered, but
when addressing malformations in frogs, the focus is typically only on single
causes and their effects on hindlimbs, and then often only on hindlimb
polymely? ...

Species Affected

Amphibian malformations are not evenly distributed across taxa. As mentioned
in Chapter 1, amphibian malformations tend to be frog malformations.
A quick count shows that 52 of 105 U.S. frog species (50%) had
documented malformations compared with 19 of 188 U.S. salamander
species (10%). ...

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